Biotin
Growth factor for nanoplankton, among other things. Is also synthesised in plants. Biotin is the coenzyme in CO₂ fixation and transcarboxylation reactions in the presence and with the participation of magnesium ions.
Biotin has 3 asymmetric C atoms, so that 8 stereoisomers are possible. However, only the D isomer is biologically active and is the only one that occurs in nature.